Biochemistry · 2000 · 79 citations · 9 references
Life SciencesBiochemistryMolecular BiologyProtein TranslationRna BiologyRna ProcessingProtein SynthesisRibosome BiogenesisTranslation ElongationTranslation In ProkaryotesTranslation InitiationTranslational RegulationElongation Factor Tu FunctionEukaryotic Elongation FactorsRna-binding Proteins In TranslationTranslation Elongation ControlTranslation Elongation FactorsTranslation Elongation KineticsTranslation KineticsTurnover Number
Aminoacylation and transportation of tmRNA to stalled ribosomes constitute prerequisite steps for trans-translation, a process facilitating the release of stalled ribosomes from 3' ends of truncated mRNAs and the degradation of incompletely synthesized proteins. Kinetic analysis of the aminoacylation of tmRNA indicates that tmRNA has both a lower affinity and a lower turnover number than cognate tRNA(Ala) for alanyl-tRNA synthetase, resulting in a 75-fold lower k(cat)/K(M) value. The association rate constant of Ala-tmRNA for elongation factor Tu in complex with GTP is about 150-fold lower than that of Ala-tRNA(Ala), whereas its dissocation rate constant is about 5-fold lower. These observations can be interpreted to suggest that additional factors facilitate tmRNA binding to ribosomes.
9